The electronics industry is a rapidly growing field and considerable research is being done in the industry to make electronic components smaller and faster. To accomplish this the density of the components on the chip must be increased. Polymer coatings (resists) are the first step in creating the patterns on the chip and are, therefore, critically important. The resist forms these patterns after exposure to radiation by becoming either less soluble (negative resists) or more soluble (positive resists) to a certain solvent than the unexposed film. The resists must then withstand a variety of downstream processing steps such as etching and doping. A good and highly desirable resist should therefore have a high sensitivity to the form of irradiation used, high resolution, good adhesion to the substrate and good resistance to etching.
Presently, the forms of irradiation being used most to expose the resist are near ultraviolet (U.V.) and visible light. Without the addition of a number of time consuming processing steps, near U.V. and visible light can, at best, resolve images of about one micron due to diffraction effects of the light. To achieve the submicron features, the wavelength used must be shifted in the direction of electron beam or x-ray radiation. Of these two sources, electron-beam (E-beam) is presently the most important and is being used for mask making.
In general, the ideal resist, positive or negative, should be a glassy polymer with little or no tendency to swell during dissolution. The resist should be capable of exhibiting submicron resolution and its sensitivity to electron irradiation at 10 to 30 KeV should be in the order of 10.sup.-6 C/cm.sup.2. The resist should also be sufficiently stable to withstand a variety of etching processes such as plasma and sputter etching, ion milling, etc.
In spite of the large amount of work over the past ten years the ideal resist has not as yet been developed. Most materials are deficient in one or more of the aforementioned requirements.
At the present time the industry requires E-beam negative resists that have a sensitivity of about one .mu.C/cm.sup.2, a resolution of less than one micron (&lt;1.mu.) and a good dry etch resistance, i.e., to plasma and sputter etching, ion milling, etc. The industry also requires x-ray negative resists having a sensitivity of less than 10 mJ/cm.sup.2, a resolution of less than one micron (&lt;1.mu.) and good dry etch resistance to plasma and sputter etching, ion milling, etc.
Therefore, there exists a present need within the industry to provide resists which have the required sensitivity to their irradiation source while at the same time providing a resist that has good contrast, good resolution, good resistance to dry etching and good adhesion to the substrate.
A most welcome contribution to the art would therefore be a polymer which, when used as a resist, has good sensitivity, good contrast, good resolution, good resistance to dry etching, and good adhesion to the substrate when an x-ray or E-beam radiation source is used. Such a contribution is provided by this invention.